1. Field of the Invention
The present invention relates to a mold for joining a molded portion to an end of an extruded weather strip.
2. Description of Related Art
FIG. 1 illustrates one example of a weather strip having a molded portion which is joined to an end of an extruded weather strip. As shown, a weather strip (which is generally called a glass run) 14 is continuously attached to a door frame 10 and a door panel 11 of a motor vehicle to guide a door glass 12 to a closed or open position, and seal the door frame 10 and a peripheral edge of the closed door glass 12. This weather strip 14 is composed of extruded weather strips 14A, 14B, 14D and 14E, and molded portions 14C, 14F and 14G. The molded portion 14C joins opposed ends of the extruded weather strips 14A and 14B, the molded portion 14F joins opposed ends of the extruded weather strips 14A and 14D, and the molded portion 14G joins opposed ends of the extruded weather strips 14B and 14G.
FIG. 2 illustrates a corner portion of the weather strip 14, which is composed of the molded portion 14C. FIG. 3 is a plan view of a cavity of a conventional mold for forming the molded portion 14C, which is taken along a parting plane thereof, and FIG. 4 illustrates a cross-section one part of the cavity, which is taken along the line of 4--4 of FIG. 3.
In order to form the molded portion 14C, as shown in FIG. 3, ends of the extruded weather strips 14A and 14B are respectively placed at ends of a cavity 16. Then, a molding material is injected into the cavity 16.
As shown in FIG. 2, the molded portion 14C has a tubular sealing portion 18. This sealing portion 18 is molded in the part of the cavity 16, which is defined by an upper mold member 20A, a lower mold member 20B and a core member 20C, as shown in FIG. 4. Upon injection of a molding material, it is likely to enter the parting plane 22 between the upper mold member 20A and the lower mold member 20B, thus forming fins along upper and lower edges 18A and 18B of the sealing portion 18 of the resulting molded portion 14C. When the obtained weather strip 14 is attached to the inside of the door frame 10 (FIG. 1), the fin formed along the upper edge 18A is covered with and concealed by the door frame 10. However, the fin formed along the lower edge 18B is exposed to external view, thus degrading both the appearance of the weather strip 14 and the sealing properties thereof. Accordingly, removal of this fin is necessary, but the process of removing the fin is extremely troublesome.
In order to facilitate the removal of the fin, a mold as illustrated in FIGS. 5 and 6 has been used. As shown, a tunnel-like additional cavity 24 is formed in the parting plane 22 between the upper mold member 20A and the lower mold member 20B next to a peripheral edge of cavity 16, where the fin to be removed forms.
The ends of the additional cavity 24 are respectively located at the positions beyond the ends 28A, 28B of the weather strips 14A and 14B. A passage 26 having a narrow width of 0.11 to 0.15 mm is also formed in the parting place 22 so as to interconnect the cavity 16 with the additional cavity 24, thereby allowing the molding material injected into the cavity 16 to enter the additional cavity 24.
Due to the additional cavity 24 and the passage 26, a fin of which an edge is thick is formed along the lower edge 18B of the sealing portion 18 of the resulting molded portion 14C. This fin is easily removed by ripping it off along the thin root portion formed by passage 26 filling with molding material.
However, in this case, the joints between the molded portion 14C and the respective end surfaces 28A and 28B of the weather strips 14A and 14B are likely to become loose.
The looseness in the joints is caused when the molding material is injected, as part of the molding material escapes into the additional cavity 24. Even if a sufficient amount of the molding material is injected, taking into account the escape to the additional cavity 24, the injection pressure tends to gradually decrease toward the ends of the cavity 16. As a result, the pressure of the molding material pushing the end surfaces 28a and 28B of the extruded weather strips 14A and 14B becomes insufficient to form a good joint therebetween.
If the extruded weather strips 14A and 14B are placed so as to be offset outwardly of the cavity 16, the joints between the molded portion 14C and the extruded weather strips 14A and 14B are likely to become loose.